LVM: regenerate a UUID

LVM's performance overhead is trivial, using it twice won't change that. Your raid-5 device is going to have a much much greater impact than lvm.

It's perfectly fine to do this. What you do not want is to have the parent of the snapshot (the original, or the source, or whatever you want to call it) to be in use at the same time, because it will cause IO multiplication (Hubert was right about this, it is just easy to prevent by not using the source volume all the time).

If you have one master OS install on an LVM, and you snapshot that four times, you will not have much of an IO penalty, since you are only writing to the individual snapshot volumes. Of course, it is not free, but neither are other forms of snapshotting on other filesystems or virtual disks. There is always a cost somewhere.

One other thing Hubert is right about, is that you have to think about the sizing of your snapshots. You will want to make sure the snapshot volumes are able to keep writing. A full snapshot volume will break stuff badly. A failsafe way to prevent this, is to make the snapshot volume the same size (or bigger) than the source volume. You loose the benefit of using less diskspace this way, though.

You know that qemu images are snapshot capable too?